High Exhaust Temperature Due to Regeneration in Volvo. What’s This?

Volvo produces diesel vehicles and engines. Vehicles with diesel engines need regeneration intermittently. Regeneration removes particles and soot that build up in the Diesel Particulate Filter (DPF). The continued functioning of the engine and DPF is partly dependent on successful regeneration cycles.

For Volvo owners or operators, you might have seen the "high exhaust temperature" message in your driver information display when regeneration is ongoing. This article assesses what that message means and what you should know about it. To understand the message, you need to understand regeneration. Thus, we first briefly explain regeneration. Following that, we will explain what "high exhaust temperature" means in Volvos and what you should do.

Understanding Regeneration in Diesel Vehicles

An important component used in regulating emissions in modern diesel engines is the Diesel Particulate Filter (DPF). DPFs remove particles of solids and liquids like soot and dirt from the exhaust. DPFs are essential for complying with US Environmental Protection Agencies tier 4 and EU stage V emission regulations. Also, DPFs are crucial for protecting your vehicle from unplanned maintenance and costly breakdowns.

Particulate matter or soot is created during combustion. Soot is made up of hard carbon with a sticky outer layer that allows it to clump together. Soot then forms deposits in the cylinder walls, engine oil, turbo bearings, and other parts. There is an exhaust aftertreatment system for dealing with soot buildup in a diesel vehicle.

Within the exhaust aftertreatment system is the Diesel Oxidation Catalyst (DOC). It removes the sticky layer from the soot. Then, most of the rest of the soot is collected by the DPF, with the fine particles passing through its filter into the environment. However, with time, the DPF can become clogged by particulate matter or soot. A blocked DPF will prevent exhaust fumes from leaving the engine efficiently, creating exhaust backpressure.

Exhaust backpressure can affect engine performance and reduce fuel efficiency. It can lead to DPF failure and even damage the engine. To stop this from happening, the DPF has to be cleaned when the amount of soot in the engine reaches a particular threshold. The method Volvo and other diesel equipment manufacturers use to clean soot from the DPF is called regeneration.

Regeneration of the DPF is crucial to burn soot that will build up as time passes. Regeneration occurs at very high temperatures. The DPF has to be heated until it is hot enough to burn off the soot. Two methods of regeneration in Volvo vehicles and most diesel vehicles are passive and active regeneration.

Passive or automatic regeneration occurs as you drive, especially at high speeds. Driving at high speeds will get the exhaust hot enough to burn off the soot in the DPF. However, without driving at high speeds for a considerable time, passive regeneration may not occur or be enough to regenerate the DPF completely. For example, driving at restricted speeds inside a city may not be enough to start or complete a regeneration cycle. This is where active regeneration comes in.

Suppose you do not drive your Volvo long enough for passive regeneration to burn off all the soot. You have to use active or manual regeneration. The DPF symbol on your dashboard or driver display will indicate it needs cleaning once the differential pressure sensors in the DPF signal for regeneration. Depending on your model, you may see a message saying, "Soot filter full - see manual." Active regeneration involves flipping a switch to activate regeneration.

The switch to activate regeneration is called the DRC-AMII DPF regeneration switch in some Volvo trucks. You can start or cancel a regeneration with it. You need to park and idle your Volvo for this to work. The active regeneration switch not only activates a manual regeneration but also inhibits an ongoing passive regeneration. In addition, hitting the switch stops a manual regeneration. Make sure you read your user manual for steps to perform an active regeneration on your Volvo.

In some extreme cases, neither passive nor active regeneration will be adequate to complete the regeneration cycle. As we mentioned, the DPF being clogged can be catastrophic for the engine. In this situation, you will need a forced regeneration. Forced regens should be done by experts. However, the scope of our article is not concerned with forced regen.

What is "High Exhaust Temperature" in a Volvo?

High exhaust pressure is a message or light displayed on the driver's information display on the Volvos dashboard when the exhaust temperatures reach a high level. In many cases, the message will be "Regeneration in progress. High exhaust temperature" or something similar. This is not an error or malfunction message. Instead, it is an advisory message.

In the section where we explained regeneration, it was mentioned that regeneration occurs at very high temperatures. Temperatures in the exhaust can reach as high as 840 degrees Fahrenheit and even much higher on a larger Volvo engine. Such temperatures can melt objects or burn people. These high temperatures are necessary to complete the regeneration cycle.

What the high exhaust temperature message does is to let you know how hot the exhaust is. Awareness of high exhaust temperatures is fundamental due to the potential hazards of that level of heat. In summary, the "High exhaust temperature" indicator does the following things:

• Let's you know regeneration is ongoing
• The exhaust temperatures are high
• No additional action is required of the driver or operator

What Should You Do About "High Exhaust Temperature"?

The message goes away on its own after regeneration. There is not much you need to do when you see this message. It is normal to have this message when regeneration is ongoing. You don't need to call for help or take your vehicle to a mechanic.

However, there are some things you can be mindful about on the appearance of the high exhaust gas advisory message. Follow the guidelines below.

1) Continue Driving When Passive Regeneration Is Ongoing

If this message comes on during passive regeneration, continue driving at a good speed so as to complete the regeneration cycle. Do not turn off the engine during active or passive regeneration to avoid interrupting the regeneration process.

2) Safety Precautions

Because of the high temperatures during DPF regeneration in your Volvo, there are certain cautionary steps you can take to prevent damage to people, properties, or the environment. While there are not any known issues with the high temperatures during regeneration, you can still be mindful of some things.

• No one should be around the exhaust for any reason when "High Exhaust Temperature" is on. The temperatures in such situations are high enough to burn or cause serious injury to people. This is not the time to inspect the exhaust of your car. It is certainly not the time to perform exhaust maintenance. You will get burned.
• Avoid parking in certain areas when you have this message. Do not park around flammable terrains or items, like dry bushes or grass, so as to not accidentally start a fire. Also, avoid parking around explosive materials when this message is on. For example, do not park around propane trucks, gas tanks, or places with fuel spills.

3) Professional Help

One thing that might require you to seek professional help is if the high exhaust temperature warning light stays on for longer than expected. The time it takes for your vehicle to complete a regeneration cycle will vary with your particular model, age of the vehicle, soot level, driving conditions, etc. In a car like the 2024 Volvo XC60, automatic regeneration should take between 10 and 20 minutes, according to Volvo.

Generally, regeneration takes somewhere between 10 minutes to 1 hour based on several factors. Add an additional 5 - 10 minutes for the exhaust temperature to get back to an average level. Anything significantly over that duration might be a sign of an issue. Shut off the engine if it continues for too long. It could just be a faulty sensor. However, seek technical help to be sure.

Conclusion

The "High Exhaust Temperature Due to Regeneration" message in a Volvo is a standard indicator that the vital process of regeneration is underway. Regeneration could be passive or active. Regardless, it is necessary for clearing up the buildup of particulate matter or soot in the DPF. Do not treat the High Exhaust Temperature message as a malfunction or error. Rather, it is an advisory that keeps you aware of the current temperature status of the exhaust due to the ongoing regeneration cycle.

The high exhaust temperature message is a sign to keep driving at decent speeds if passive regeneration is ongoing. Also, it is cautionary because it alerts users to stay away from the exhaust to avoid burns. Further, when this message is active, avoid parking your Volvo around flammable items or surfaces due to the exhaust's high temperatures. The only thing that should see you seek professional help is if the "High exhaust Temperature" message stays on for longer than expected.